[GRASS-user] Tobler's hiking function

[mlage at usal.es]

Hello Glynn.
It's   6 * exp {-3.5*abs(Slope+0.05)}
So I guess it goes newmap="(6 * exp(-3.5*(abs(slopemap)+0.05)))/0.025"
0.025 it's for Distance (cell resolution). The Hiking Function estimates
distance in Km and my DEM it's 25x25m.
Do you think this syntax is correct, now?
Thank you.
Miguel Lage.


----- Original Message -----
From: "Glynn Clements" <glynn at gclements.plus.com>
To: <mlage at usal.es>
Cc: <grassuser at grass.itc.it>
Sent: Friday, January 26, 2007 5:16 AM
Subject: Re: [GRASS-user] Tobler's hiking function


>
> mlage at usal.es wrote:
>
>> Thank you very much, Glynn.
>> The original Hiking Function is:
>>
>> W= 6 exp {-3.5*abs(Slope + 0.05)}
>>
>> Through this I want to estimate anisotropic cost movements in friction
>> surfaces.
>> Maybe the problem is that I haven't understood the r.mapcalc syntax...
>
> My problem is that I don't understand your syntax; what does "X exp Y"
> mean?
>
> --
> Glynn Clements <glynn at gclements.plus.com>
>